Samsung DVD+RW 4.7GB 4X disc is neither rewritable or erasable.
Drive LED just flashes while that particular DVD is in the drive.
All other CD's and DVD's are operational.

Nero sees the DVD as having 0 Total Capacity / Sessions / Tracks.

Any ideas?

Was it used previously and accidentally closed so no more sessions can be done as would be with a CDr or DVDr? Try viewing it with whatever you use for dvds other than the burning program.

Or go to My Computer> Right click on the drive where the dvd is and click Explore. Any luck?

It was used before and it was accidentally closed while writing a multisession. Was not being finalized since it "was" a rewritable.
Using Explorer, shows 0 space / 0 used / 0 capacity.

Think i hosed a rewritable. :)
I was hoping it could be undone, but it acts as a Read-Only disc and the drive LED is flashing.

Edit:
Actually, the last command used was Full-Erase. Took 15 minutes and after that, it's never been the same.